Electric vehicle supply equipment with temperature controlled current

ABSTRACT

In electric vehicle supply equipment (EVSE), interruption of charging due to overheating is prevented by adjusting the pulse duty cycle on the control pilot conductor communicating the maximum allowed current level to the electric vehicle, the adjustment being performed whenever the EVSE temperature exceeds a predetermined threshold temperature below the maximum operating temperature as a function of the approach of the temperature to the maximum operating temperature.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/875,909, filed Oct. 6, 2015 entitled PORTABLE CHARGING CABLE WITHIN-LINE CONTROLLER, by David Paul Soden, et al., which is a continuationof U.S. patent application Ser. No. 13/639,910, filed Apr. 4, 2013, nowU.S. Pat. No. 9,156,362, entitled PORTABLE CHARGING CABLE WITH IN-LINECONTROLLER, by David Paul Soden, et al., which is the National Stage ofInternational Application No. PCT/US11/31843, filed Apr. 8, 2011entitled PORTABLE CHARGING CABLE WITH IN-LINE CONTROLLER, by David PaulSoden, et al., which claims the benefit under 35 USC §119(e) of U.S.Provisional Application No. 61/322,807, filed Apr. 9, 2010 entitledL1/L2 CORD SET & POWER DANGLE, by Albert Joseph Flack, et al., andclaims the benefit of U.S. Provisional Application No. 61/434,282, filedJan. 19, 2011 entitled LEVEL 1-2 PORTABLE EV CHARGER CABLE, by DavidPaul Soden, et al., and claims the benefit of U.S. ProvisionalApplication No. 61/437,001, filed Jan. 27, 2011 entitled PORTABLEELECTRIC VEHICLE CHARGING CABLE WITH IN-LINE CONTROLLER, by David PaulSoden, et al., and claims the benefit of U.S. Provisional ApplicationNo. 61/467,068, filed Mar. 24, 2011 entitled PORTABLE CHARGING CABLEWITH IN-LINE CONTROLLER, by David Paul Soden, et al. All of the aboveapplications are hereby incorporated by reference in their entirety.

TECHNICAL FIELD

The invention concerns electric supply equipment such as home-chargingdevices for electric vehicles.

BACKGROUND

Electric vehicle supply equipment (EVSE) for residential charging of anelectric vehicle (EV) is implemented at present as stationary unitsconnected to the electric utility grid through a household electricutility panel, and are not readily portable. The possibility of a lossof battery power when the EV is far from a commercial recharging stationor personal home charging equipment is a problem that has not beensolved.

SUMMARY

A portable electric vehicle support equipment (EVSE) unit is formed as acord of plural insulated conductors and a flexible outer sheathenclosing said plural insulated conductors. The cord includes an EVSEdocking connector on a docking end of the cord and a utility plug on autility end of the cord, said cord being divided into a docking sectionterminated at said docking connector and a utility section terminated atsaid utility connector. The cord further includes an in-line EVSEcontroller and a housing enclosing said controller, said housing sealedwith said flexible outer sheath and disposed at an intermediate sectionof said cord between said docking and utility sections. The in-line EVSEcontroller is connected in series between conductors of said dockingsection and conductors of said utility section. In one embodiment, thesheath and said housing form a continuous outer seal. The housing issealed with a portion of said sheath enclosing said docking section orit is sealed with portions of said sheath enclosing both said dockingand utility sections.

In embodiments, the housing is joined with said utility and dockingsections at opposing ends of the housing, said housing being suspendedbetween said docking and utility sections of said cord so as to befreely movable with the cord. In one embodiment, the housing has aslength of about 5-6 inches, a width of about 3-4 inches and a height ofabout 0.5-2 inches and has a mass less than the mass of said dockingsection of said cord.

In embodiments, said housing includes a pair of congruent upper andlower half shells having respective outer side walls, each of said halfshells having a pair of half openings at opposite ends of the respectivehalf shell, annular portions of said docking and utility sections beingcompressed between edges of facing ones of said half openings. Thein-line controller may include a circuit board having electricalcomponents connected to conductors of said docking and utility sectionsof said cord, and a potting compound encapsulating said circuit boardbetween said half shells.

In embodiments, the housing further includes a bumper formed of anelastically deformable material and surrounding the outer side walls ofsaid half shells. The bumper has holes in registration with said halfopenings. The bumper may be integrally formed and may include an annularouter case and an annular interior belt surrounded by said outer case,said annular interior belt comprising an upward facing lip and adownward facing lip, an upper bumper groove being defined between saidouter case and said upper facing lip and a lower bumper groove beingdefined between said outer case and said downward facing lip. The upperand lower half shells may comprise respective interior walls parallelwith the respective ones of said outer side walls and forming respectiveupper and lower shell grooves. The upward facing lip is compressed insaid upper shell groove, and said downward facing lip is compressed insaid lower shell groove. The edge portions of the respective outer sidewalls are pressed inside respective ones of said upper and lower bumpergrooves.

In embodiments, the outer case comprises a pair of opposing arcuate endskirts and a pair of straight gripping saddles joining said end skirts,each of said end skirts having a first height extending above a ceilingof said upper half shell and below a floor of said lower half shell,said gripping saddles having a second height less than said firstheight, to provide free air flow around the housing as its rests on asurface. The outer case of said bumper forms a bumper side wall, saidbumper side wall comprising an annular convex apex that promotesrotation of the housing whenever it is placed on one of its side edges.

In embodiments, there is a control pilot conductor in said dockingsection of said cord, and said in-line EVSE controller comprises amicroprocessor comprising a serial port, an analog buffer coupledbetween said microprocessor and said control pilot conductor, and aconductor connected between said serial port and said control pilotconductor. In further embodiments, the in-line controller furtherincludes a pulse generator coupled to said control pilot conductor andhaving a duty cycle controlled by said microprocessor, signifying amaximum current limit, and a temperature sensor having a temperatureoutput coupled to said microprocessor, said temperature outputrepresenting a present temperature. In embodiments, said microprocessoris programmed to reduce charging current flow through said EVSE cordwhenever said present temperature exceeds a predetermined limit, byadjusting said duty cycle in response to said present temperatureapproaching a predetermined temperature limit.

In further embodiments, a method is provided for communicating digitaldata between said in-line controller of the EVSE cord and an externaldigital device, said method comprising coupling a serial port of amicroprocessor of said in-line controller to a conductor of said cordthat runs between said in-line controller and said docking connector,and coupling a serial port of an external digital device to saidconductor by connection to said docking connector. The external digitaldevice may be any one of a personal computer, a notebook computer, acell phone, a personal digital assistant, or an interface tool dedicatedto external connection with said docking conductor.

In embodiments, the method may further include downloading from saidmicroprocessor to said digital device via said serial port anidentification of firmware stored in said in-line controller,determining whether said firmware has been superseded, and uploadingfrom said digital device to said microprocessor via said serial port andvia said conductor a current version of said firmware.

In related embodiments, the method may include downloading from saidmicroprocessor to said digital device status data representative ofconditions in or status of said EVSE cord, interpreting said status dataand generating an image representing a meaning of said status data on adisplay of said digital device. The data may be downloaded on arequest-only basis or as a constant stream.

In an alternative embodiment, the EVSE cord is connected to the EV, andthe method includes downloading from said microprocessor via said serialport to the EV digital device status data representative of conditionsin or status of said EVSE cord, interpreting said status data andgenerating an image representing a meaning of said status data on adisplay of said EV.

In another embodiment, the utility connector may be adapted to connectto different outlets of different voltages (e.g., 120 VAC and 240 VAC),and the method further includes sensing at a sensor in said in-linecontroller a utility voltage received through said utility connector,determining in said processor which one of plural predetermined voltageranges said utility voltage is closest to, and setting said onepredetermined voltage range as the allowed voltage range. The processormay issue a fault alarm whenever an output of said sensor indicates saidutility voltage is outside of said one predetermined range. In a relatedembodiment, the system designer may have previously correlated thedifferent possible utility voltages to different maximum allowablecurrent levels. The method controls the pulse duty cycle imposed on thecontrol pilot conductor to signify a maximum current level, and setssaid duty cycle to a current level previously correlated to said onepredetermined voltage range.

In another embodiment, an EVSE kit is provided consisting of the EVSEcord and an interface tool providing external access to the serial portthrough the control pilot conductor. The interface tool includes (1) atool enclosure, (2) an EV connector mounted on said tool enclosure forconnection with said control pilot conductor, and (3) a serial portconnector mounted on said tool enclosure and adapted to receive a serialport connector from an external digital device. The EVSE dockingconnector can be connected to the charging port of an EV whenever the EVis to be charged and can be connected to said interface tool wheneverdigital communication with said in-line controller is to be performed.

In an alternative embodiment, the interface tool may be a stand-alonehandheld device that includes a processor in said tool enclosure, adisplay disposed on said tool enclosure, said display controlled by saidprocessor, said processor comprising a serial port coupled to thecontrol pilot conductor whenever the EVSE cord and the interface toolare connected to one another. The interface tool may also include a keypad on said interface tool enclosure. Alternatively, or in addition, thedisplay of said interface tool is a touch screen for user communicationwith said processor.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the exemplary embodiments of the presentinvention are attained and can be understood in detail, a moreparticular description of the invention, briefly summarized above, maybe had by reference to the embodiments thereof which are illustrated inthe appended drawings. It is to be appreciated that certain well knownprocesses are not discussed herein in order to not obscure theinvention.

FIG. 1 depicts the portable charging cable of one embodiment.

FIG. 2 is a simplified block diagram depicting internal elements of theportable cable of FIG. 1.

FIG. 3 is a simplified block diagram depicting elements in the charginginterface of an EV connected to the portable charging cable of FIG. 1.

FIG. 4 is a flow diagram depicting a method performed in the embodimentof FIG. 1 for automatically adjusting to different utility supplyvoltages.

FIG. 5 is a simplified block diagram depicting an embodiment in whichthe portable cable facilitates file uploading from an external computerthrough a special interface tool.

FIG. 5A is an orthographic view of a robust handheld embodiment of thespecial interface tool of FIG. 5.

FIG. 5B is a simplified schematic block diagram of the special interfacetool of FIG. 5A.

FIGS. 6A and 6B together constitute a flow diagram depicting methods ofoperation in the embodiment of FIG. 5.

FIG. 7 is a block diagram depicting the contents of a memory used in themethods of FIGS. 6A and 6B.

FIG. 8 is a flow diagram depicting methods of operating the embodimentsof FIGS. 1-3 for prevention of overheating in the in-line controller ofFIG. 1 during EV charging.

FIG. 9 is an orthographic view of one embodiment.

FIG. 10 is an enlarged view corresponding to FIG. 9.

FIG. 11 is an exploded orthographic view of the embodiment of FIG. 10.

FIG. 12 is an enlarged detailed view of a bumper depicted in FIG. 11.

FIG. 13 is a cut-away end view corresponding to FIG. 10.

FIG. 14 is an elevational side view corresponding to FIG. 10.

FIG. 15 includes elevational end views corresponding to FIG. 10 atdifferent rotational positions.

FIG. 16 is a cross-sectional elevational side view corresponding to FIG.10.

FIG. 17 is a cut-away end view of an exploded assembly corresponding toFIG. 10.

FIGS. 18A, 18B and 18C are orthographic views of different fastenersemployed in the embodiment of FIG. 17.

FIG. 19 is a cut-away elevational side view corresponding to FIG. 10depicting a first embodiment of cable strain relief.

FIG. 20 is a cut-away elevational side view corresponding to FIG. 10depicting a second embodiment of cable strain relief.

FIG. 21 is an orthographic view corresponding to a portion of FIG. 10and depicting a third embodiment of cable strain relief.

FIGS. 22A, 22B and 22C are cut-away end views corresponding to FIG. 21depicting sequential compression of a cable fitting.

FIGS. 23A, 23B and 23C depict alternative shapes of cable openingsproviding strain relief, including a hexagonal opening (FIG. 23A), anoctagonal opening (FIG. 23B) and a square or diamond-shaped opening(FIG. 23C).

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements and features of oneembodiment may be beneficially incorporated in other embodiments withoutfurther recitation. It is to be noted, however, that the appendeddrawings illustrate only exemplary embodiments of this invention and aretherefore not to be considered limiting of its scope, for the inventionmay admit to other equally effective embodiments.

DETAILED DESCRIPTION

Embodiments of the present invention facilitate charging an EV usingcommonly available electricity outlets with a cable that functions as alight transportable EVSE unit. The light transportable EVSE unit can beeasily carried in an EV and independently used at remote locations tocharge the EV from standard electric power outlets. Electrical andelectronic components required to perform the functions of an EVSE areintegrated into the cable that constitutes the light transportable EVSEunit, in one embodiment.

Referring to FIG. 1, the light transportable EVSE unit, in oneembodiment, is an intelligent portable charging cable 100. The exteriorsurface of the cable 100 is formed by a a cylindrical flexible sleeve ofan insulating material such as rubber or flexible plastic, for example.The cable 100 contains multiple insulated conductors described belowwith reference to FIG. 2. In FIG. 1, a docking end 100 a of the portablecharging cable 100 has a docking connector 105 connectable to an EVcharging port 107 of an EV 109. A utility end 100 b of the portablecharging cable 100 has a 240 Volt AC plug 110 connectable to a standard240 Volt AC power outlet 113 a. Optionally, a 120 Volt-to-240 Volt plugadapter 112 connectable to a standard 120 Volt AC power outlet 113 b maybe tethered to the utility end 100 b of the cable 100. The portablecharging cable 100 further includes a programmable in-line controller115 situated at an intermediate location between the docking end 100 aand the utility end 100 b and interrupting the conductor paths withinthe portable charging cable 100. The in-line controller 115 thus dividesthe portable charging cable 100 into a docking cable section 100-1 and autility cable section 100-2. The in-line controller 115 provides theportable charging cable 100 with the complete functionality of aconventional EVSE unit, including the capability to perform charging ofan EV and to perform the communication protocols required by the EVon-board systems. For this purpose, the in-line controller 115 includescircuit elements and programmable controller elements adapted toimplement the required functionality, as will now be described.

Referring to FIGS. 1 and 2, the cable docking section 100-1 contains apair of insulated power conductors 202 a, 204 a extending from thedocking connector 105 to and into one side of the in-line controller115. The cable utility section 100-2 contains a pair of insulated powerconductors 202 b, 204 b extending from the plug 110 to and into anopposite side of the in-line controller 115. Within the in-linecontroller 115, a pair of contactors 206, 208 provide interruptibleconnection between the power conductors 202 a, 202 b and between thepower conductors 204 a, 204 b, respectively. The contactors 206, 208 areactuated by an actuator 207 which may be a solenoid or other suitabledevice, and will be referred to herein as a solenoid.

Communication between in-line controller 115 and the EV 109 is carriedover a control pilot conductor 209 of the docking section 100-1 of thecable 100. Such communication may be implemented in accordance with thecommunication protocols defined in Section 5.3 of the Society ofAutomotive Engineers Specification SAE J1772. A neutral groundedconductor 211 extends through the entire length of the portable chargingcable 100. The neutral grounded conductor 211 may correspond to utilityground at the connector 110. Each of the conductors 202 a, 204 a, 209and 211 is connected to a corresponding conductive pin (not shown)inside the docking connector 105.

The in-line controller 115 may include various sensors, such as aground-fault coil sensor 210, a sensor 212 connected to the powerconductors 202 b, 204 b and adapted to sense voltage (and/or phaseand/or frequency) of the power from the power outlet 113, and atemperature sensor 214 to monitor temperature inside the in-linecontroller 115. Operation of the in-line controller 115 is governed by acomputer or processor 216. Each of the sensors 210, 212 and 214 has anoutput connected to an input of the processor 216. The processor 216 hasa central processing unit (CPU) or microprocessor 217 and a memory 218storing a set of program instructions in the form of firmware. Themicroprocessor 217 executes the program instructions to perform variousfunctions including implementing the required communication protocolswith the on-board systems of the EV. If the communication protocols arethose defined in Society of Automotive Engineers Specification SAEJ1772, they are implemented by the EVSE and the EV imposing a sequenceof voltage changes on the control pilot conductor 209. For this purpose,analog circuitry 220 is coupled between the microprocessor 217 and thecontrol pilot conductor 209 that enables the microprocessor 217 toimpose the required voltage changes on the control pilot conductor 209(and to sense voltage changes imposed on the control pilot conductor 209by the internal systems of the EV 109). Pulse modulation of the voltageon the control pilot conductor 209 is performed by a pulse generator 222whose pulse duty cycle is controlled by the microprocessor 217. Thepulse duty cycle signifies to the EV the maximum allowable chargingcurrent that may be drawn from the EVSE.

If the microprocessor 217 determines from the sensor 212 that theutility cord section 100-2 is connected to a voltage of 120 volts, thenthe microprocessor 217 sets the pulse duty cycle to a value signifying aparticular current level (e.g., a Level 1 current level defined by SAEJ1772). If the microprocessor 217 determines that the utility cordsection 100-2 is connected to a voltage of 240 volts, then themicroprocessor 217 may set the pulse duty cycle to a value signifyinganother current level (e.g., a Level 2 current defined by SAE J1772).Such current levels may be predetermined in accordance with the currentratings of the components of the portable charging cable 100,particularly the current ratings of the 220 Volt plug 110 and the 120Volt adapter 112 of FIG. 1.

The D.C. voltage on the control pilot conductor 209 is controlled andsensed through the analog circuitry 220 by the microprocessor 217 inaccordance with the required communication protocol. The microprocessor217 controls the solenoid 207 to open or close the contactors 206, 208.The microprocessor 217 monitors the outputs of the ground faultinterrupt sensor 210, the voltage/frequency/phase sensor 212 and thetemperature sensor 214 to determine whether any conditions arise thatare outside of a prescribed set of conditions (e.g., voltage beyond aprescribed range, temperature outside of a prescribed range, groundfault occurrence, etc.), and if so, opens the contactors 206 and 208.Such an occurrence may be indicated under control of the microprocessor217 on a user interface or by external lights or light emitting diodes(LEDs) 117 provided on the in-line controller 115 as shown in FIG. 1.The light patterns for different conditions may be specified for theuser.

FIG. 3 is a simplified diagram depicting certain components of the EV109 of FIG. 1 and their connection through the EV charging port 107 tothe EVSE 100 of FIG. 1. These components include a battery pack 352 anda charge controller or battery management unit 354. In addition, analogcircuitry 356 may be provided to enable the charge controller 354 torespond to and impose changes in voltage on the control pilot conductor209 through the EV connector 107. This feature enables the chargecontroller 354 to respond appropriately to changes in voltage on thecontrol pilot conductor 209 in accordance with the requiredcommunication protocol referred to above.

As described above with reference to FIG. 1, the plug 110 may beconfigured for insertion into a standard 240 volt A.C. outlet, and anoptional 240 volt/120 volt adapter 112 may be tethered to the cableutility end 100 b to permit connection to a standard 120 volt A.C.outlet. Thus, the source voltage may be either 120 VAC or 220 VAC.

The in-line controller 115, in one embodiment described below herein,automatically detects (through the sensor 212) the voltage input throughthe cable utility end 100-2, and ascertains the appropriate voltagerange, which is either Level 1 (i.e., 120 VAC±10%) or Level 2 (i.e., 240VAC±10%). Once the appropriate range has been ascertained, themicroprocessor 217 constantly compares the actual voltage measured bythe sensor 212 with the appropriate voltage range, and issues an alarmor halts charging whenever (for example) an over-voltage conditionoccurs. Therefore the portable charging cable 100 can be operated as aLevel 1 or Level 2 EVSE depending upon the attached plug connector.

FIG. 4 depicts one method for automatically adapting to the voltagerange. In this method, the microprocessor continually monitors theutility supply voltage using the sensor 212 (block 240 of FIG. 4). Themicroprocessor 217 determines whether the sensed voltage is closer to120 VAC—“Level 1”, or 240 VAC—“Level 2” (block 242). If the sensedvoltage is closer to 120 VAC (YES branch of block 242), then themicroprocessor 217 establishes the allowable voltage range as 120VAC±10% (block 244 a). If the sensed voltage is closer to 240 VAC (NObranch of block 242), then the microprocessor 217 establishes theallowable voltage range as 240 VAC±10% (block 244 b).

In a further aspect, the designer may have established a maximumallowable current level, which may be the same for both possible voltageranges (i.e., Level 1 and Level 2) or may be different for the tworanges. For example, the maximum allowable current level may be higherfor the Level 2 voltage range than for the Level 1 voltage range, totake advantage of the higher current levels allowed by the specificationSAE J1772 for Level 2 voltages, and to account for any difference incurrent ratings between the 240 Volt plug 110 and the tethered 120 Voltadapter 112 of FIG. 1. The microprocessor 217 sets the maximum allowablecurrent level (block 248 of FIG. 4), which may depend upon whether theallowable voltage range is a Level 1 voltage or a Level 2 voltage. Themicroprocessor 217 sets the pulse generator 222 to a duty cyclecorresponding to the maximum allowable current level (block 250).

The microprocessor 217 monitors the current using the output of thesensor 212 (block 252) and produces an alarm and a trouble code if thecurrent exceeds the limit (block 254). The microprocessor 217 continuesto monitor the utility supply voltage, and if the sensed voltagedeviates outside of the allowable voltage range, the microprocessor 217generates a fault alarm to the user and stores a corresponding troublecode in the memory 218 (block 255).

In an alternative embodiment, the portable charging cable 100 may beconfigured to accept only 120 volt A.C. power, and can be provided as acombination of the in-line controller 115 and the docking cable section100-1 without the utility cable section 100-2. In this alternativeembodiment, in place of the utility cable section 100-2 is a socket onthe in-line controller 115 for attaching a conventional 120 voltextension cord. In this simplified configuration, a user would be ableto charge the EV from commonly available electrical outlets usingreadily available equipment. In a further configuration of the aboveembodiment, the extension cord may include GFI (ground faultinterrupter) circuitry.

A housing or enclosure 230 provides a permanent water-proof seal aroundthe exterior of the in-line controller 115, as indicated in FIG. 2. Thehousing 230 may have flat and/or curved exterior surfaces (not shown inFIG. 2). The in-line controller 115 may be an integral part of the cable100. The housing occupies an intermediate zone of the cable 100 betweenthe docking section 100-1 and the utility section 100-2. Alternatively,each cable section 100-1 and 100-2 may be detachably connected tooptional ports 115-1, 115-2, respectively, on opposite ends of thehousing 230. In one embodiment, the housing 230 may be integrated with(or sealed with) the exterior surfaces of the cable docking section100-1 and the cable utility section 100-2. The housing 230 may comprisea plastic or metal enclosure. The interior of the housing 230 maycontain the electronic and electrical components of the type depicted inFIG. 2. In addition, a potting compound may fill the empty spaces insidethe housing 230 and thereby provide thermal conduction from the interiorcomponents to the exterior of the housing 230. In one embodiment, thehousing 230 may be formed by potting the components of the in-linecontroller 115 with a potting compound. The embodiments of the housing230 are described later in this specification.

The housing 230 is an integral part of the cable 100 and is freelysuspended between the cord docking and utility sections 100-1, 100-2whenever cord is lifted or moved, so that the entire cord 100 includingthe housing 230 behaves mechanically as a single integrated cord duringhandling or moving. The housing 230 is sufficiently small and light tobehave as an integral part of cord during handling. In embodiments, thehousing 230 may have length in the range of 5-6 inches, a width in therange of 3-4 inches and a height in the range of 1.0-2.5 inches. Thecord docking section 100-1 may be about 15-25 feet long. The corddocking and utility sections 100-1, 100-2 have circular cross-sectionsof diameter between 0.25 and 1.0 inch, while the housing 230 has arectangular cross-section.

File Uploading/Downloading Via Control Pilot Serial Port:

One advantage of permanently sealing the components of the in-linecontroller components within the housing 230 is that the in-linecontroller 115 is protected from moisture, mechanical shock, electricalshock and tampering. However, this feature prevents accessing theelectronic components of the in-line controller 115. This would prevent,for example, conducting simple tests or fetching information from thememory 218 to determine, for example, whether the firmware or computerprograms stored in the memory 218 are the latest version. Suchencapsulation also prevents uploading new software into the memory 218or replacing existing software.

This limitation is overcome by providing for serial data transfer fromand to the microprocessor 217 over the control pilot conductor 209.Referring now to FIG. 5, the microprocessor 217 has a serial port 400that provides serial data transfer in accordance with a suitable serialdata transfer protocol such as Universal Serial Bus (USB) or RS232. Theappropriate driver firmware may be stored in the memory 218 to enablethe microprocessor 217 to implement data transfer via the control pilotconductor 209 in both directions. A serial bus or conductor 410 connectsthe serial port 400 with the control pilot conductor 209. The controlpilot conductor 209 thus functions as (A) a communication channel forthe analog D.C. voltage level changes by which the EVSE and the EVcommunicate with each other and (B) a two-way serial bus for digitalcommunication.

External access to the serial port 400 via the control pilot conductor209 is provided through a stand-alone interface tool 415 shown in FIG.5. The interface tool 415 has an interface tool connector port 420 ableto mate with the EVSE connector 105 whenever the EVSE connector 105 isnot mated to the EV charging port 107. Whenever the EVSE connector 105is mated with the interface tool connector port 420, one pin 420 a ofthe interface tool connector port 420 is coupled to the control pilotconductor 209, while a second pin 420 b is coupled to the neutralconductor 211. A user-accessible serial port 425, such as a USB port, isprovided on the interface tool 415 and is connected to the pins 420 aand 420 b through internal conductors inside the interface tool 415.

Whenever it is desired to communicate with the microprocessor 217 orverify contents of the memory 218 or to perform file transfers (e.g., toupload a latest revision of firmware) to the microprocessor 217 and/ormemory 218, the EVSE connector 105 is disconnected from the EV chargingport 107 and connected instead to the interface tool connector port 420.The interface tool connector port 420 provides for connection betweenthe control pilot conductor 209 and the user-accessible serial port 425.The serial port 425 may be implemented as a USB connector which may beconnected to a computer 430 (e.g., a personal computer or a notebookcomputer) or to a handheld programmable communication device 435, suchas a PDA (personal digital assistant) or a smart phone or equivalentdevice. Both the processor 216 and the computer 430 (or PDA 435) containrespective firmware program instructions that enable a user to performvarious tasks, such as downloading and interpreting EVSE trouble codes,verifying the software version of programs stored in the memory 218,deleting obsolete software stored in the memory 218 and uploadingupdated versions of the software from the computer 430 or PDA 435 to thememory 218. The character representation of each EVSE trouble code andthe conditions under which it is to be issued by the microprocessor 217are predetermined by the system designer.

In some cases, provision may be made for the EV 109 to transmitdiagnostic trouble codes to the EVSE. In this case, if the EVSE is theportable charging cable 100 of FIG. 1, these trouble codes may be storedin the memory 218 of the in-line controller 115, and later (when the EV109 and EVSE 100 are no longer connected) downloaded through theinterface tool 415 for evaluation or diagnosis by a technician.

The interface tool 415 may be provided as a portable tool that the usermay store at home. The interface tool 415 may be provided as standardequipment stored in the EV along with the portable charging cable 100.The interface tool 415 may be provided in a kiosk at a vehicle dealerfor example, that can be visited by the user. The interface tool 415 maybe provided as a professional technician's tool for use by repairfacilities or dealers. In this latter case, the interface tool 415 mayinclude most or all of the functionality of a computer 430 (including amicroprocessor and memory, a display, and program firmware fordownloading and interpreting trouble codes), so as to be aself-contained hand-held diagnostic tool. Software updates may beobtained by the computer 430, the handheld communication device 435, orby the interface tool 415 itself, via a communication channel such as adedicated radio link, a local area network or via the internet.

FIGS. 5A and 5B depict a versatile handheld embodiment of the interfacetool 415. FIG. 5A depicts how the interface tool may be shaped whileFIG. 5B depicts its internal architecture. In FIG. 5A, the interfacetool 415 includes the connector port 420. The connector port 420 may becompatible with the type specified by the Society of AutomotiveEngineers Specification SAE J1772, for connection to the dockingconnector 105 of the EVSE 100 of FIGS. 1-3 and 5. The interface tool ofFIGS. 5A and 5B further includes a microprocessor 436, a memory 437 anda display or video monitor screen 438. The microprocessor 436 includes aserial port 436 a that is connected to the connector port pins 420 a,420 b to facilitate communication with the EVSE's microprocessor 217.The microprocessor 436 controls the display 438 and is coupled to thememory 437. The memory 437 stores firmware including an operating system437 a, a USB driver 437 b for communication with the EVSE'smicroprocessor 217 and a video driver 437 c for controlling the display438. In addition, the memory 437 may store diagnostic firmware 437 denabling the microprocessor 436 to interpret trouble codes and statusdata received from the EVSE microprocessor 217 and to generaterepresentative images on the display 438 that enable the user tounderstand the status of the EVSE 100 and to understand the troublecodes. A communication module 439 coupled to the microprocessor 436enables the microprocessor 436 to access new information via acommunication network such as the internet or a local area network(e.g., within a facility such as a vehicle dealership). For example, thecommunication module 439 may include conventional wireless local areanetworking hardware. A keypad 440 may be provided on the interface tool415 to enable the user (e.g., a technician) to enter commands to theEVSE microprocessor 217 (e.g., requesting a particular data transfer orinformation) and/or to respond to prompts on the display 438 generatedby the diagnostic firmware. The display 438 may be a touch screen,enabling the user to communicate to the microprocessor 436. In thiscase, the key pad 440 may not be required.

The information obtained from the EVSE 100 by the interface tool 415 mayinclude the current status of the EVSE 100 (e.g., temperature withinrange, supply voltage within range, frequency within range, no GFEfaults, etc.). This information may be displayed on a monitor of thecomputer 430 or on a display screen of the PDA 435, for example. Or, ifthe interface tool 415 is the versatile embodiment of FIGS. 5A and 5B,then the information may be displayed on the screen or display 438 ofthe interface tool 415.

In an alternative embodiment, the information obtained from themicroprocessor 217 via serial data communication on the control pilotconductor 209 may be displayed on the driver's display of the EV 109.This would be possible whenever the EVSE docking connector 105 isconnected to the EV charging port 107, not to the interface tool 415. Insuch a case, an on-board computer of the EV 109 may be programmed toobtain the information through the EV battery management system. Withregard to such a feature, the EV 109 of FIG. 3 includes a serial port358 that is coupled to the control pilot conductor 209 of the EVSE 100whenever the EVSE 100 is connected to the EV 109. In addition, FIG. 3depicts further elements of the EV 109, including an on-board computer360 and an EV driver display 362 controlled by the on-board computer360. The on-board computer 360 may access firmware 364 that enables itto communicate with the battery management system 354 to obtaininformation via the serial port 358 (or the on-board computer 360 maycommunicate directly with the serial port 358). In this way, during thetime that the EV 109 is being charged by the EVSE 100, informationconcerning the status of the EVSE 100 may be displayed on the EV driverdisplay 362. As noted above, the displayed information may includecurrent status of the EVSE 100, a history of past trouble codes,identification of the firmware version stored in the EVSE memory 218,and related information.

FIGS. 6A and 6B depict methods using the control pilot conductor as aserial bus to communicate digital information to and from the EVSEmemory 218 and microprocessor 217 using the interface tool 415 of FIG.5A with the computer 430 or using the interface tool of FIGS. 5A and 5B.The operations depicted in FIGS. 6A and 6B rely upon the EVSE memory 218containing certain components as depicted in FIG. 7.

Referring to FIG. 7, the components stored in the memory 218 may includean operating system 400, and a set of instructions 402 that may be usedcontrol the microprocessor 217 to perform particular data transferoperations. These operations may include downloading specifiedinformation in the memory 218, erasing specified locations in the memory218, and uploading new files to specified locations in the memory 218.The components stored in the memory 218 may further include a firmwarepackage or program 404 that enables the microprocessor 217 to performthe required communication protocols and charge the EV 109 in accordancewith the required procedures. The memory 218 may further contain aprogram 406 that enables the microprocessor 217 to generate appropriatetrouble codes whenever a fault (or condition violating the requirementsof a controlling specification) is detected. The memory 218 may alsocontain a list of allowed voltage ranges 408, current limits 410,temperature limits 412 and a may contain a USB driver 414.

Referring again to FIGS. 6A and 6B, a first operation (block 500) is todownload data or information files from the memory 218 to the computer430 via the control pilot conductor 209 serial port 400 using theinterface tool 415. There are various tasks this operation can perform.A first task may be for the computer 430 to download the data transferinstruction set of the microprocessor 217 via the serial port 400 (block502). This would enable the user to select the proper instruction tocommand the microprocessor 217 to perform specific data transfer tasks.One such task may be to download current trouble codes (block 504),which may be used, for example, in testing the EVSE 100 in the absenceof the EV 109. Another task may be to download the present EVSE status(block 506). This task may be performed in one of three modes, dependingupon the command asserted by the computer 430: (1) manually, uponrequest (block 508), (2) continuously, in streaming mode (block 510),and (3) an automatic dump of information upon status change (block 512).

A further download task may be to download the entire history of troublecodes stored in the memory 218 (block 514). Another download task may beto download from the memory 218 the identity (or date) of the firmwarecurrently stored in the memory 218 (block 516) to determine whether ithas been superseded or needs updating.

A next operation using the control pilot conductor 209 as a serial databus is to display the downloaded information (block 520). This operationmay use the display on a screen of the computer 430 or on a display orscreen of the PDA 435 (block 522). The downloaded information may bedisplayed on the interface tool display screen 438 of FIG. 5A (block524). In an alternative embodiment, the downloaded information isdisplayed on the EV driver display 362 of FIG. 3 (block 526 of FIG. 6).In this embodiment, the EVSE docking connector 105 is connected to theEV charging port 107, not to the interface tool 415. The information tobe displayed is communicated to the EV on-board computer 360 via thecontrol pilot conductor 209 (block 528).

A third type of operation is to upload program files to the memory 218via the control pilot conductor 209 (block 530). The uploaded files maybe furnished from a computer 430 or PDA 435 connected to the interfacetool 415. Alternatively, the uploaded program files may be furnished bythe interface tool 415 itself, using its communication module 439, forexample. A first step is to connect the docking connector 105 to theinterface tool 415. If necessary, the interface tool 415 is connected tothe computer 430 or PDA 435, in the manner illustrated in FIG. 5 (block532). The next step is for the computer 430 (or PDA 435) to obtain thelatest firmware files from a source, for example over the internet(block 534). The memory 218 may be cleared by erasing selected (or all)firmware files previously loaded into the memory 218 (block 536). Theoperation is completed by writing the new files to the memory 218 (block538).

Because of the compact size and insulation of the in-line controller115, it may operate at fairly high internal temperatures, which need tobe controlled in order to avoid overheating. In accordance with afurther aspect, the microprocessor 217 may be programmed to preventshutdown of the charging operation due to overheating of the in-linecontroller 115 of FIG. 1. It does this by reducing the charging currentbefore the temperature reaches the maximum allowed limit. Specifically,the EVSE microprocessor 217 (FIG. 2) may be programmed to override thenominal setting of the pulse duty cycle and reduce the duty cycle of thepulse generator 222, in response to the output of the temperature sensor214 exceeding a predetermined threshold temperature (e.g., 70 degreesC.) that is 10%-30% below the maximum operating temperature of themicroprocessor 217 (e.g., 85 degrees C.). It does this so as to reducethe charging current (set by the pulse duty cycle) by an amountproportional to the approach of the measured temperature to the maximumoperating temperature of the microprocessor 217 (e.g., 85 degrees C.).The nominal pulse duty cycle is stored in the memory 218 at onelocation, the predetermined threshold temperature is stored in thememory 218 at another location and the maximum operating temperature isstored in the memory 218 at third location. The reduction in chargingcurrent may be by an amount proportional to the rise of the measuredtemperature above the predetermined threshold temperature. The operationis represented as a series of program instructions stored in the memory218 and executed by the microprocessor 217, and is illustrated in FIG.8.

Referring now to FIG. 8, the EVSE cable 100 and the EV 109 perform theprescribed handshake protocol via the control pilot conductor 209 afterthe docking connector 105 has been inserted into the EV charging port107 (block 710 of FIG. 8). The duty cycle of the pulse generator 222 isset to the maximum allowable current draw that was previously determinedby the system designer (block 715). The output of the temperature sensor214 is sampled to obtain a present temperature of inside the EVSE 100(block 720). A comparison of the present temperature to thepredetermined threshold temperature (e.g., 70 degrees C.) is performed(block 725). If the present temperature is below the predeterminedthreshold temperature (YES branch of block 725), then the operationreturns to the step of block 715. Otherwise (NO branch of block 725),the present temperature is compared with the maximum operatingtemperature (e.g., 85 degrees C.) in block 730. If the presenttemperature is less than the maximum operating temperature (YES branchof block 730), then the microprocessor 217 overrides the previously setnominal duty cycle value and reduces the duty cycle from the nominalvalue by a factor proportional to either the ratio between the measuredpresent temperature and the maximum operating temperature or thedifference between them (block 735). In the unlikely event that themeasured temperature exceeds the maximum operating temperature (NObranch of block 730), charging is halted (block 740), and the operationreturns to the step of block 720. The occurrence of such an event isunlikely because the onset of charging current reduction (block 735)occurs at the predetermined threshold temperature, which is 10% to 30%below the maximum operating temperature. Thus, in the examples providedherein, the predetermined threshold temperature may be 70 degrees C. fora maximum operating temperature of 85 degrees C.

In an exemplary embodiment, the step of block 735 may be performed byreducing the control pilot pulse duty cycle by a factor F, so that theduty cycle is changed from the current duty cycle D by multiplying D by(1−F), so that the new duty cycle is (1−F)D. F depends upon the presenttemperature sensed by the sensor 214. One example of how to define F isas follows:

F=(present temp−70 deg C.)/(85 deg C.−70deg C.),

where “present temp” is the measured temperature from the sensor 214 indegrees C., 85 deg C. is the maximum operating temperature, and 70 degC. is the predetermined threshold temperature. The skilled worker mayuse suitable definitions of F other than the foregoing.

Sealed Encapsulating Housing:

In an embodiment, the in-line controller 115 is permanently sealedwithin the housing 230 from any external moisture or gas. The housing230 may include elastically deformable materials, such as rubber, thatinsulate the in-line controller 115 from shock and vibration. In oneembodiment, the housing 230 may be filled with a potting compound thatprovides a thermal path from the electrical and electronic components ofthe in-line controller 115 to the external surfaces of the housing 230.In another embodiment, the housing 230 itself is formed as a solidvolume of potting compound that encapsulates the components of thein-line controller 115.

One embodiment of the housing 230 is illustrated in FIGS. 9-16. FIG. 9is an orthographic view of the EVSE cable 100 including the housing 230,while FIG. 10 is an enlarged view corresponding to FIG. 9. FIG. 11 is anexploded orthographic view corresponding to FIG. 10. FIG. 12 is anenlarged detailed view of a bumper depicted in FIG. 11. FIG. 13 is acut-away end view corresponding to FIG. 10. FIG. 14 is an elevationalside view corresponding to FIG. 10. FIG. 15 includes elevational endviews corresponding to FIG. 10 showing the housing 230 at differentrotational orientations. FIG. 16 is a cut-away elevational side view ofa completed assembly corresponding to FIG. 11.

In the embodiment illustrated in FIGS. 9-16, the housing 230 includes ashell 600 as indicated in FIG. 9. As shown in FIG. 11, the shell 600 isformed as two matching halves, namely a top half shell 602 and a bottomhalf shell 604, both preferably formed of a hard high-impact material,which may be plastic, metal, alloy, carbon fiber or other syntheticmaterial. The top half shell 602 has a ceiling 602 a and a side wall 602b, while the bottom half shell 604 has a floor 604 a and a side wall 604b. There are exposed edges 602 c, 604 c of the side walls 602 b and 604b that are generally congruent with one another. The ceiling 602 a andfloor 604 a are generally flat while the side walls 602 b and 604 bfollow a “racetrack shape” defined by long straight edges 602 c-1, 604c-1, respectively, and short curved edges 602 c-2, 604 c-2,respectively. The top half shell 602 has half-circle openings 606 a, 606b at respective ends of the side wall 602 b. Similarly, the bottom halfshell 604 has half-circle openings 608 a, 608 b at respective ends ofthe side wall 604 b. The half circle openings form circular openings607, 609 (shown in FIG. 16) at the respective ends of the shell 600 whenthe two half shells 602, 604 are mated. The top and bottom half shells602, 604 have structurally reinforcing interior ribs 610, 611,respectively, extending in transverse direction to opposite sides. Theribs 610 of the bottom half shell 604 are visible in the view of FIG.11, and there are corresponding ribs 611 in the top half shell 602visible in FIG. 16. Interior reinforcing posts 612 extend from the floor604 a to the ceiling 602 a are each divided into separate half posts, ofwhich the bottom half posts 612 b extending from the floor 604 a arevisible in the view of FIG. 11, while the top half posts 612 a are shownin FIG. 16 and in hidden line in FIG. 11.

A circuit board 614 supports the electrical and electronic components ofthe in-line controller 115 previously described herein with reference toFIGS. 2 and 3. The circuit board 614 is held within the interior volumeformed between the two half shells 602, 604, as shown in FIG. 11. Thecircuit board 614 has a pair of holes 616 a, 616 b through which thereinforcing posts 612 extend. The components mounted on the circuitboard 614 are the components of the in-line controller 115 of FIGS. 1and 2, and include the light emitting diodes 117 previously referred toherein, and transparent covers 118. LED holes 622 in the ceiling 602 aare in registration with the LEDs 117 and are sealed by respectiveO-rings 119. Permanent fasteners 620 a through 620 d provide permanentattachment between the top and bottom half shells 602, 604, as isdescribed below in greater detail.

As best seen in the view of FIG. 13, the top half shell 602 has aninterior side wall 626 parallel to the side wall 602 b and forming anupper groove 628 between the two side walls 602 b and 626. In likemanner, the bottom half shell 604 has an interior side wall 630 parallelto the side wall 604 b and forming a lower groove 632 between the twoside walls 604 b and 630.

A bumper 634 formed of an elastically deformable material, such asrubber, surrounds the side walls 602 b, 604 b. As shown in FIGS. 11-13,the bumper 634 consists of an outer case 634 a and an interior belt 634b generally parallel with the outer case 634 a. The interior belt 634 bforms upper and lower lips 634 b-1 and 634 b-2 that fit within the upperand lower grooves 628, 632, respectively. The outer case 634 a and theupper lip 634 b-1 form an upper bumper groove 636 between them, whilethe outer case 634 a and the lower lip 634 b-2 form a lower bumpergroove 638 between them. A lip of the upper side wall 602 b is held inthe upper bumper groove 636, with some elastic deformation of the upperbumper groove 636, while a lip of the lower side wall 604 b is held inthe lower bumper groove 638, with some elastic deformation of the lowerbumper groove 638.

The outer case 634 has a pair of arcuate end skirts 640, 642 coveringthe short curved edges 602 c-2, 604 c-2, respectively, of the side walls602 c, 604 c. The outer case 634 further includes gripping saddles 644,646 covering the long straight edges 602 c-1, 604 c-1, respectively, ofthe side walls 602 c, 604 c. The arcuate end skirts 640, 642 have amajor height, H (FIG. 12), extending above the plane of the ceiling 602a and below the plane of the floor 604 a, while the gripping saddles644, 646 have a minor height, h (FIG. 12) that is less than H. As shownin FIGS. 13 and 14, this feature enables air to flow freely around andunderneath the shell 600 whenever the unit is resting on a surface, forimproved cooling, because the end skirts 640, 642 hold the shell 600above the surface. A hole 648 in the end skirt 640 is in registrationwith the hole 607 formed by the half circle openings 606 b, 608 b in thehalf shells 602, 604, respectively. A hole 649 in the end skirt 642 isin registration with the hole 609 formed by the half circle openings 606a, 608 a in the half shells 602, 604, respectively. The end skirts 640,642 have arcuate convex crests 640 a, 642 a. The effect of this featureis illustrated in FIG. 15, in which the in-line controller 115 tends torotate until it rests on one of its major faces after being placed onits edge. This rotation places the in-line controller 115 in thestrongest orientation to resist compression if stepped on or run over bya vehicle.

FIG. 17 illustrates how the permanent fasteners 620 a through 620 d aretightly received into holes 656 in the upper half shell 602 and holes658 in the lower half shell 604. FIGS. 18A, 18B and 18C illustratedifferent embodiments of the permanent fasteners 620 that may beinserted into the holes 656, 658, including an expandable insert (FIG.18A), a barbed insert (FIG. 18B), and a press-fit insert (FIG. 18C).With the foregoing features, the two half shells 602, 604 arepermanently attached by pressing them together, and the fastening cannotbe undone.

FIG. 19 depicts one type of cable strain relief that may be employed toisolate the electrical connections (between the conductors in each cable100-1, 100-2 and components on the circuit board 614) from tension onthe cables 100-1, 100-2. FIG. 19 is a view of one of the two circularopenings 607, 609 at each end of the shell 600 depicting a structurethat is common to both. An interior end of a hollow cylinder 660 isthreadably engaged inside the circular opening 607. At its exterior end,the hollow cylinder 660 protrudes outwardly from the shell 600 and isdivided into plural compressible leaves 662. The cable (100-1 or 100-2)extends through the hollow cylinder 660. A nut 664 is threadably engagedaround the exterior end of the hollow cylinder 660 and compresses theplural leaves 662 together against the outside surface of the cable100-1 or 100-2 as the nut is tightened onto the hollow cylinder. Incompressing the outer surface of the cable 100 in this manner providesan integral seal between each cable section 100-1, 100-2 and the housing230, so that the housing 230 and the cable sections 100-1, 100-2 form anintegral cable.

FIG. 20 depicts another cable strain relief feature that may be usedalone or in combination with the cable strain relief feature of FIG. 19.FIG. 20 is a view of one of the two circular openings 607, 609, anddepicts a structure that is common to both. In FIG. 20, the upper halfshell 602 has a downwardly extending post 670 near the circular opening607, while the lower half shell 604 has an upwardly opening socket 672in registration with the post 670. The post 670 deflects the cable(100-1 or 100-2) into the socket 672, bending the cable by apredetermined amount that is compatible with the flexibility of thecable. Optionally, a hollow cylinder or bushing 674 may surround thecable and be threaded or bonded into the hole 607 (or 609).

In one alternative embodiment, only the cable (100-1 or 100-2) isinserted through the hole (607 or 609), and the hole is sized so thatits edge compresses the outer insulator of the cable, thereby providingcable strain relief.

In another alternative embodiment depicted in FIG. 21, an elastic orplastic hollow fitting 680 fits around the exterior of the cable 100-1(100-2). The fitting 680 has a circular groove 682 that receives theedges of the two half circular openings 606, 608. The fitting 680 mayinclude a flexible conical section 684 that provides relief from lateralbending of the cable. In a further aspect, the two half circularopenings 606, 608 may not be circular, but instead may be non-circular,to enhance compression of the cable 100-1 (in one embodiment) or of thefitting 680 (in another embodiment). One shape of a non-circular openingis depicted in FIG. 22A, at a point in time before the two half shells602, 604 are brought together. As the two half shells 602, 604 are movedtoward one another (FIG. 22B), the fitting 680 begins to deform until itconforms to the non-circular shape of the opening when the two halfshells 602, 604 are mated (FIG. 22C). In compressing the outer surfaceof the cable 100 in this manner provides an integral seal between eachcable section 100-1, 100-2 and the housing 230, so that the housing 230and the cable sections 100-1, 100-2 form an integral cable.

FIGS. 23A, 23B and 23C depict alternative shapes of cable openings 606,608 providing strain relief, including a hexagonal opening (FIG. 23A),an octagonal opening (FIG. 23B) and a square or diamond-shaped opening(FIG. 23C).

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

What is claimed is:
 1. An electric vehicle supply equipment (EVSE)system for charging an electric vehicle, comprising: a utility connectorcomprising a first pair of power conductors; a docking connectorcomprising a second pair of power conductors, said docking connectorbeing engagable with a charging port of an electric vehicle; a pair ofcontactors between said first and second pairs of power conductors; aprocessor and a memory accessible by said processor, said pair ofcontactors under control of said processor; a control pilot conductorextending through said docking connector; a pulse generator coupled tosaid control pilot conductor and having a pulse duty cycle controlled bysaid processor; a temperature sensor having an output representative ofa present temperature, said output coupled to said processor; saidmemory containing: (a) a nominal pulse duty cycle corresponding to anominal value of maximum allowable current, (b) a predeterminedthreshold temperature, said processor programmed to reduce the pulseduty cycle of said pulse generator from said nominal pulse duty cycle bya reduction factor that is a function of an increase of said presenttemperature above said predetermined threshold temperature.
 2. The EVSEsystem of claim 1 wherein said function is a proportional function. 3.The EVSE system of claim 1 wherein said memory further contains amaximum operating temperature.
 4. The EVSE system of claim 3 whereinsaid reduction factor is a function of the closeness of said presenttemperature to said maximum operating temperature.
 5. The EVSE system ofclaim 3 wherein said predetermined threshold temperature is in a rangeof 10% to 30% of said maximum operating temperature.
 6. The EVSE systemof claim 1 wherein the electric vehicle responds to a change in pulseduty cycle by changing current draw accordingly.
 7. An electric vehiclesupply equipment (EVSE) system, comprising: a utility connectorcomprising a first pair of power conductors; a docking connectorcomprising a second pair of power conductors, said docking connectorbeing engageable with a charging port of an electric vehicle; a pair ofcontactors between said first and second pairs of power conductors; aprocessor and a memory accessible by said processor, said pair ofcontactors under control of said processor; a control pilot conductorextending through said docking connector; a pulse generator coupled tosaid control pilot conductor and having a pulse duty cycle controlled bysaid processor; a temperature sensor having an output representative ofa present temperature, said output coupled to said processor; saidmemory storing: (a) a nominal pulse duty cycle corresponding to anominal value of maximum allowable current, (b) a maximum operatingtemperature, said processor programmed to reduce the pulse duty cycle ofsaid pulse generator from said nominal pulse duty cycle by a reductionfactor that is a function of the closeness of said present temperatureto said maximum operating temperature, whenever said present temperatureexceeds a predetermined threshold temperature.
 8. The EVSE system ofclaim 7 wherein said function is a proportional function.
 9. The EVSEsystem of claim 7 wherein said predetermined threshold temperature is ina range of 10% to 30% of said maximum operating temperature.
 10. TheEVSE system of claim 7 wherein the electric vehicle responds to a changein pulse duty cycle by changing current draw accordingly.